Marine and submarine pipelines

ABSTRACT

This invention relates to improvements in marine, which includes submarine, apparatus, such as pipelines and associated equipment. Marine apparatus formed of equipment assembled around which are at least one insulation assembly, wherein the said at least one assembly circumferentially surrounds the equipment and comprises at least one shroud providing an impermeable enclosure filled with thermal insulation, the thermal insulation being totally enclosed by the shroud around and over its external surface and end surfaces, and by the equipment at its internal surface, the at least one shrouded insulation assembly being a discrete length and are adjoined end to end.

This invention relates to improvements in marine, which includessubmarine, apparatus, such as pipelines and associated equipment.

For the recovery of hydrocarbon from beneath the seabed, it has beennecessary to install prefabricated pipelines within and between offshoreoil and gas fields and onshore processing facilities.

To meet the need to install pipelines with a high degree of reliability,it is possible to use barges and vessels with several aligned welding,inspection and coating stations that can fabricate a pipeline from alarge number of short lengths, typically 11 metres long. The weldedjoints of the pipeline have then to be inspected and coated before thepipeline is lowered to the seabed down and over a curved stinger orramp. As an alternative, suitable for pipelines of smaller diameter, thepipelines will be fabricated into long lengths, which are then reeledonto a large drum or spool on board a vessel. The pipeline is unreeledfrom the vessel, straightened to remove the curvature created by thereeling process, and then lowered onto the seabed.

A further alternative is to fabricate, at a suitable shore site, abundled assembly formed of a pipeline or group of pipelines housedwithin a large diameter outer steel pipeline, known as a carrier pipe.The void space within the carrier pipe and around the inner pipelines issealed to prevent seawater ingress and to provide buoyancy. The bundledassembly is then towed from the shore site to the offshore site, wherethe carrier is then flooded.

In use, pipelines and associated equipment often need to be insulated tomaintain temperatures of the fluid flowing within them. Thermalinsulation of the equipment is currently provided by the application tothe outside surface of the pipeline or equipment of one or a pluralityof layers of suitable insulation material. These insulation materialsare typically elastomers, which are applied to the pipeline by variousprocesses including extrusion, impingement or wrapping.

A further alternative, where high levels of thermal insulation isrequired, is to house a pipeline within an outer sleeve pipe, theannulus between which is filled either totally or partially withinsulation material. This method of providing thermal insulation, isknown as a ‘Pipe-in-Pipe’ arrangement. The ‘Pipe-in-Pipe’ arrangement isparticularly appropriate for installation in deep water and/or operationat high temperatures and pressures.

It is an objective of the present invention to provide a marine andsubmarine apparatus, including pipelines and associated equipment withan alternative form of high performance thermal insulation, which doesnot need to be housed within an outer sleeve Pipe-in-Pipe arrangement.

According to the invention there is provided thermal insulation formarine or submarine apparatus, typically a pipeline, comprisinginsulation material housed within a totally enclosing shroud. Thetotally enclosing shroud may be formed by casting the shroud around thepre-formed half shells of thermal insulation which are first secured tothe pipeline. Alternatively the totally enclosing shroud is bonded orsecured to the pipeline prior to filling it with thermal insulation. Afurther alternative is to provide thermal insulation by fabricating halfshell shrouds which are themselves filled with thermal insulationmaterial, the shrouded half shells are then either bonded ormechanically secured to the pipeline outer surface, to totally enclosethe pipeline. The totally enclosing shroud or shrouded half shells arepre-formed in discrete lengths, 1.5 or 2 metres in length beingappropriate to facilitate application. The shrouded shells may beproduced by casting, rota-moulding or fabricated of pre-formed partseach produced typically by casting, rota-moulding, extrusion, injectionmoulding and the like. The shrouded shells may feature suitable endarrangements to abut, adjoin and lock together to form an elongateassembly of thermal insulation along part or the whole length of thepipeline.

It is common practice to weld together the short length (circa 12 mlong) pipe joints to form what is termed double or quad joints orstrings, comprising two and four pipe length respectively. For bundlesand pipelines to be installed by reeling, the string length may extendto several kilometers. It is envisaged that it will often be the casethat the thermal insulation half shells will be applied over the entirelength of the strings, save a short distance at each end to facilitatewelding (the field jointing) the pipe strings together to form thepipeline. Upon completion of the field joint it too will be thermallyinsulated. To achieve this a number of systems can be utilised,including ones based on the embodiments of this invention.

Whilst reference is made throughout this document to half shells, theshrouded thermal insulation assemblies may be formed as one or aplurality of assemblies, including but not limited to third or quartershells by way of example, to circumscribe or surround the pipe.

It is understood that the term ‘apparatus’ refers to individual piecesof equipment, structures, pipelines, flow lines, conduits orcombinations of the aforesaid and the like.

Preferred embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross section of a piece of underwater equipment accordingto the invention which is surrounded by thermal insulation housed withina discrete length enclosing shroud and as also illustrated in FIG. 9;

FIG. 2 is a cross section of a piece of underwater equipment asdescribed above with reference to FIG. 1, which features a plurality oflongitudinal bulkheads;

FIG. 3 is a cross section of a piece of underwater equipment accordingto the invention which is surrounded by thermal insulation housed withina discrete length of totally enclosing shroud and as also illustrated byFIG. 11;

FIG. 4 is a cross section of a piece of underwater equipment asdescribed above with reference to FIG. 3, which features a plurality oflongitudinal bulkheads;

FIG. 5 is a cross section of a piece of underwater equipment accordingto the invention which may be surrounded by thermal insulation housedwithin two shrouded half shells and as also illustrated by FIG. 9;

FIG. 6 is a cross section of a piece of underwater equipment accordingto the invention as described above with reference to FIG. 5, where thethermal insulation is totally encapsulated within each halt shellitself, and as also illustrated by FIG. 11;

FIG. 7 is a cross section of a piece of underwater equipment accordingto the invention as described above with reference to FIG. 5, whichfeatures a plurality of longitudinal bulkheads;

FIG. 8 is a cross section of a piece of underwater equipment accordingto the invention as described above with reference to FIG. 6, whichfeatures a plurality of longitudinal bulkheads;

FIG. 9 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIGS. 1, 2, 5, and 7;

FIG. 10 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIGS. 1, 2, 5, 7 and 9, which featuresa plurality of circumferential bulkheads;

FIG. 11 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIGS. 3, 4, 6, and 8;

FIG. 12 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIGS. 3, 4, 6, 8 and 11, whichfeatures a plurality of circumferential bulkheads;

FIG. 13 is a cross section of either the piece of underwater equipmentaccording to the invention and as described above with reference toFIGS. 1 through 12, showing typical abutting and adjoining discretelengths of half shell shroud assemblies;

FIG. 14 is a cross section of either the piece of underwater equipmentaccording to the invention and as described above with reference toFIGS. 1 through 12, showing typical abutting and adjoining discretelengths of totally enclosing shroud assemblies, including those formedof half shell shrouds, featuring a spigot arrangement, in which thejoint may be completed by bonding together any number of its adjoiningsurfaces and/or may feature one or a plurality of seals, typically ‘O’rings;

FIG. 15 is a cross section of either the piece of underwater equipmentaccording to the invention and as described above with reference toFIGS. 1 through 12, showing typical abutting and adjoining discretelengths of totally enclosing shroud assemblies, including those formedof halt shell shrouds, featuring a screw thread arrangement, wherein thejoint may be completed by bonding together any number of its adjoiningsurfaces;

FIG. 16 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIG. 1 through 15 inclusive, whichfeatures thermal insulation encapsulated in its own thin membraneshroud;

FIG. 17 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIG. 1 through 16 inclusive, whichfeatures stiffening or mass providing members incorporated between thethermal insulation and encapsulated thermal insulation, and beneath theouter most fabric of the shroud;

FIG. 18 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIG. 1 through 17 inclusive, whichfeatures integral stiffening webs formed as part of the shroud fabric.

FIG. 19 is a side elevation of the piece of underwater apparatusdescribed about with reference to FIGS. 1, 2, 5, 7, 9, 10, 13, 14, 15,16, 17, and 18 which features mass providing members or material betweenthe thermal insulation, ends of the shroud and the apparatus; and

FIG. 20 is a side elevation of the piece of underwater apparatusdescribed above with reference to FIGS. 3, 4, 6, 8, 11, 12, 13, 14, 15,16, 17, and 18 which features mass providing members or material betweenthe thermal insulation, inner surface of shroud and the apparatus.

Referring to FIG. 1 there is shown an item of underwater equipment (2),such as a piece of pipeline, which is surrounded by thermal insulation(3) and an enclosing impermeable shroud (1). The thermal insulation (3)may be preformed of shells which are secured to the equipment (2) andaround which is then cast the shroud (1). Alternatively the shroud (1)may be preformed, slid over the equipment (2), secured by bonding and/ormechanical means to the equipment (2), then filled with the thermalinsulation (3) In all cases the thermal insulation is totally bounded bythe equipment (2) and by the shroud both on its external cylindricalsurface and end surfaces as illustrated with reference to FIG. 9. By wayof example only, the thermal insulation may comprise blown polyurethanefoams, mineral wool, microporous silica, microspheres as granularmaterial or combined with a bonding agent, such as a resin or elastomer,to form a matrix material, where the interstitial voids around andbetween the microspheres are partially or totally filled with thebonding agent. Alternatively the thermal insulation may comprise aplurality of layers of any of the aforenamed insulation materials, inany combination and arrangement.

The length of the insulation assemblies can be typically anything up toaround 12m long.

Referring to FIG. 2 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) and a enclosingimpermeable shroud (1), all as particularly described above withreference to FIG. 1, which also features a plurality of longitudinalbulkheads (4). The bulkheads may be either positioned between thethermal insulation or formed when casting the enclosing shroud (1). Thereference to bulkheads also includes webs.

Referring to FIG. 3 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) and a enclosingimpermeable shroud (1), all as particularly described above withreference to FIG. 1, where the thermal insulation (3) is totallyenclosed within the shroud, both around its external surfaces and in anannulus between the equipment (2) and thermal insulation (3), as alsoillustrated with reference to FIG. 11.

Referring to FIG. 4 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) and a enclosingimpermeable shroud (1), all as particularly described above withreference to FIG. 3, which also features a plurality of longitudinalbulkheads (4). The bulkheads may be either positioned between thethermal insulation or formed when casting the enclosing shroud.

Referring to FIG. 5 there is shown an item of underwater equipment (2),to which is attached a pair of half shell assemblies, each comprising anouter impermeable shroud (1) and containing thermal insulation (3). Thethermal insulation may comprise blown polyurethane foams, mineral wool,microporous silica, microspheres as granular material or combined with abonding agent to form a matrix material, where the interstitial voidsaround and between the microspheres is partially or totally filled withthe bonding agent. Alternatively the thermal insulation may comprise aplurality of layers of any of the aforenamed insulation materials, inany combination and arrangement. The shrouds (1) and/or thermalinsulation (3) of the shells are bonded together at their adjoiningsurfaces. The shrouds and shell may also be bonded to the apparatus (2).In all cases the thermal insulation is totally bounded by the equipment(2) and by the shroud both on its external cylindrical surface and endsurfaces as illustrated with reference to FIG. 9.

Referring to FIG. 6 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) and a enclosingimpermeable shroud (1), all as particularly described above withreference to FIG. 5, but where the thermal insulation (3) is totallyenclosed within the shroud, both around its external surfaces, betweenthe equipment (2) and thermal insulation (3), its radial surfaces andits end surfaces also as illustrated by FIG. 11.

Referring to FIG. 7 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) and an enclosingimpermeable shroud (1), all as particularly described above withreference to FIG. 5, which also features a plurality of longitudinalbulkheads (4). The bulkheads may be either preformed and positionedbetween the thermal insulation (3) or formed when casting the enclosingshroud, such that they become an integral part of the shroud.

Referring to FIG. 8 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) and an enclosingimpermeable shroud (1), all as particularly described above withreference to FIG. 5, which also features a plurality of longitudinalbulkheads (4). The bulkheads may be either be preformed and positionedbetween the thermal insulation (3) or formed when casting the enclosingshroud, such that they become an integral part of the shroud.

Referring to FIG. 9 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) as particularly describedwith reference to FIGS. 1, 2, 5 and 7, where the thermal insulation (3)extends from one end of the enclosing shroud to the other end of theshroud. In all cases the thermal insulation is totally bounded by theequipment (2) and by the shroud both on its external cylindrical surfaceand end surfaces as illustrated.

Referring to FIG. 10 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) as particularly describedwith reference to FIGS. 9, where the thermal insulation (3) comprises aplurality of discrete lengths between which are circumferentialbulkheads (5). The bulkheads may be either be preformed and positionedbetween the thermal insulation (3) or formed when casting the enclosingshroud, such that they become an integral part of the shroud.

Referring to FIG. 11 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) as particularly describedwith reference to FIGS. 3, 4, 6, and 8, where the thermal insulation (3)is totally enclosed within the shroud, around its external surfaces,between the equipment (2) and thermal insulation (3) and its endsurfaces. The section of shroud (1) between the equipment (2) and thethermal insulation (3) may be completed before or as a consequence ofits assembly onto the equipment (2). The formation of the section ofshroud (1) between the equipment (2) after its assembly onto theequipment (2) thus extending the entire length of the shroud. Theformation of the inner part of the shroud in this way may at the sametime bond it into place onto the apparatus (2).

Referring to FIG. 12 there is shown an item of underwater equipment (2),which is surrounded by thermal insulation (3) as particularly describedwith reference to FIG. 11, where the thermal insulation (3) comprises aplurality of discrete lengths between which are circumferentialbulkheads (5). The bulkheads may be either be preformed and positionedbetween the thermal insulation (3) or formed when casting the enclosingshroud, such that they become an integral part of the shroud.

Referring to FIG. 13 there is shown an item of underwater equipment (2),which is surrounded by two shrouded thermal insulation elements asparticularly described with reference to FIGS. 1 through 12 inclusiveand shown adjoined at their ends and featuring a flanged arrangement.The method of joining the elements will depend on the requirements totransmit loads across the joints and may be formed as an integral partof the shroud. The configuration shown in FIG. 13 is only possible wherethe shroud is formed in shells or sections. The joint may be completedby bonding together any number of its adjoining surfaces.

Referring to FIG. 14 there is shown an item of underwater equipment (2),which is surrounded by two shrouded thermal insulation elements asparticularly described with reference to FIGS. 1 through 12 inclusiveand shown adjoined at their ends featuring a spigot arrangement. Themethod of joining the elements will depend on the requirements totransmit loads across the joints and is formed as an integral part ofthe shroud. The joint may be completed by bonding together any number ofits adjoining surfaces and may additionally feature mechanical sealingdevices such as ‘O’ rings between one or any number of its adjoiningsurfaces.

Referring to FIG. 15 there is shown an item of underwater equipment (2),which is surrounded by two shrouded thermal insulation elements asparticularly described with reference to FIGS. 1 through 12 inclusiveand shown adjoined at their ends featuring a screw thread or similararrangement. The method of joining the elements will depend on therequirements to transmit loads across the joints and is formed as anintegral part of the shroud. The joint may be completed by bondingtogether any number of its adjoining surfaces.

Referring to FIG. 16 there is shown an item of underwater equipment (2),as particularly described with reference to FIGS. 9 through 12, wherethe thermal insulation (3) is itself either totally or partiallyencapsulated in a thin membrane shroud, typically formed of suitableelastomeric material.

Referring to FIG. 17 there is shown an item of underwater equipment (2),as particularly described with reference to FIGS. 9 through 12 and FIG.16, where the shrouded thermal insulation assembly additionally featuresa stiffening ring (11), the purpose of which is to provide structuralstiffening to resist hydrostatic pressure induced forces when submerged,and/or to provide additional mass to counteract buoyancy forcesresulting from the presence of the thermal insulation and shroud. Thestiffening ring may typically be made of steel, other metals or of aelastomeric material, elastomeric material filled with heavy particulatematerial, typically iron ore or similar. Additionally the stiffeningrings may each extend beyond the ends of the thermal insulation (3) intothe shroud (1).

Referring to FIG. 18 there is shown an item of underwater equipment (2),as particularly described with reference to FIGS. 1 through 17, wherethe shroud (1) has one or a number stiffening webs formed as an integralpart of its external wall or fabric. The stiffening webs may becircumferential or longitudinal in orientation or a combination of both.

Referring to FIG. 19 there is shown an item of underwater equipment (2)as particularly described with reference to FIGS. 1, 2, 5, 7, 9, 10, 13,14, 15, 16, 17, and 18 which additionally features mass providingmembers or material between the thermal insulation (3), ends of shroud(1) and the apparatus (2). The mass providing members or material may besteel, other metals, or of a elastomeric material, elastomeric materialfilled with heavy particulate material, typically iron ore or similar.The mass providing material may typically be in the form of shells, aspiral wrap or introduced into the annulus formed between the thermalinsulation and ends of shroud following its or their assembly on to andaround the equipment. Additionally the mass providing members ormaterial may be bonded to the equipment, the thermal insulation, ends ofshroud or all three.

Referring to FIG. 20 there is shown an item of underwater equipment (2)as particularly described with reference to FIGS. 3, 4, 6, 8, 11, 12,13, 14, 15, 16, 17, and 18 which additionally features mass providingmembers or material between the thermal insulation (3), inner surface ofshroud (1) and the apparatus (2). The mass providing members or materialmay be steel, other metals, or of a elastomeric material, elastomericmaterial filled with heavy particulate material, typically iron ore orsimilar. The mass providing material may typically be in the form ofshells, a spiral wrap or introduced into the annulus formed between thethermal insulation and shroud inner surface following its or theirassembly on to and around the equipment. Additionally the mass providingmembers or material may be bonded to the equipment, the thermalinsulation, ends of shroud or all three.

1. Marine apparatus formed of equipment assembled around which are atleast one insulation assembly, wherein the said at least one assemblycircumferentially surrounds the equipment and comprises at least oneshroud providing an impermeable enclosure filled with thermalinsulation, the thermal insulation being totally enclosed by the shroudaround and over its external surface and end surfaces, and by theequipment at its internal surface, the at least one shrouded insulationassembly being a discrete length and are adjoined end to end.
 2. Marineapparatus as claimed in claim 1 in which the length of the at least oneinsulation assembly lies in the range of up to 12 metres.
 3. Marineapparatus as claimed in claim 1 in which the at least one assemblyextends the total length or part length of the equipment.
 4. Marineapparatus as claimed in claim 1 in which the at least one insulationassembly is/are bonded to an external surface of the equipment. 5.Marine apparatus as claimed in claim 1 in which the shroud of the atleast one thermal insulation assembly additionally extends the length ofeach of the at least one assembly, in an annulus formed between thethermal insulation and the equipment.
 6. Marine apparatus as claimed inclaim 1 in which the at least one thermal insulation assembly comprisesa plurality of adjoining and affixed sub-assemblies.
 7. Marine apparatusas claimed in claim 6 in which the sub-assemblies comprise shells orpart sections thereof.
 8. Marine apparatus as claimed in claim 6 inwhich the sub-assemblies are half circumferential.
 9. Marine apparatusas claimed in claim 6 in which the sub-assemblies are each bonded at aninterface surface with a circumferentially adjacent sub-assembly, aswell as to the equipment.
 10. Marine apparatus as claimed in claim 6 inwhich the shroud of each sub-assembly additionally extends the length ofthe said sub-assembly in an annulus formed between the thermalinsulation and the equipment such that the shroud totally encloses thethermal insulation of each sub-assembly.
 11. Marine apparatus as claimedin claim 1 in which bulkheads are incorporated between and within thethermal insulation to support the shroud.
 12. Marine apparatus asclaimed in claim 11 in which the bulkheads comprise an integral part ofthe shroud.
 13. Marine apparatus as claimed in claim 11 in which thebulkheads are separately assembled with the shroud.
 14. Marine apparatusas claimed in claim 1 in which the thermal insulation and/or itsenclosing shroud(s) is secured to the equipment.
 15. Marine apparatus asclaimed in claim 1 in which the thermal insulation is bonded to theshroud.
 16. Marine apparatus as claimed in claim 1 in which the thermalinsulation is formed of foamed elastomer.
 17. Marine apparatus asclaimed in claim 1 in which the thermal insulation is formed of mineralwool.
 18. Marine apparatus as claimed in claim 1 in which the thermalinsulation is formed of microporous silica.
 19. Marine apparatus asclaimed in claim 1 in which the thermal insulation is formed of hollowmicrospheres.
 20. Marine apparatus as claimed in claim 19 in which voidspace within the enclosure and interstitial void space around andbetween the microspheres is filled or partially occupied with fineparticle solids.
 21. Marine apparatus as claimed in claim 19 in whichvoid space within the enclosure and interstitial void space around andbetween the microspheres is filled or partially occupied with a solidmatrix.
 22. Marine apparatus as claimed in claim 19 in which void spacewithin the enclosure and interstitial void space around and between themicrospheres is filled or partially occupied with a liquid.
 23. Marineapparatus as claimed in claim 19 in which void space within theenclosure and interstitial void space around and between themicrospheres is filled or partially occupied with a gas.
 24. Marineapparatus as claimed in claim 19 in which void space within theenclosure and interstitial void space around and between themicrospheres is filled or partially occupied with a vacuum.
 25. Marineapparatus as claimed in claim 1 in which the thermal insulation isformed of any combination or arrangement of the materials claimed inclaims 16 to
 24. 26. Marine apparatus as claimed in claim 1 in which thethermal insulation is housed within its own part or total enclosureprior to assembly within the shroud.
 27. Marine apparatus as claimed inclaim 1 in which stiffening or mass providing members are incorporatedbetween the thermal insulation and its enclosing shroud.
 28. Marineapparatus as claimed in claim 27 in which the stiffening or massproviding members extend in length into the shroud.
 29. Marine apparatusas claimed in claim 1 in which a plurality of shrouded thermalinsulation assemblies are adjoined and fixed.
 30. Marine apparatus asclaimed in claim 29 in which a plurality of shrouded thermal insulationassemblies are adjoined and affixed by a connecting means.
 31. Marineapparatus as claimed in claim 30 in which the connecting means betweenthe shrouded assemblies comprise at least one seal.
 32. Marine apparatusas claimed in claim 29 in which the plurality of shrouded thermalinsulation assemblies are bonded at adjoining surfaces.
 33. Marineapparatus as claimed in claim 30 in which the connecting means isconfigured to conform a structural bulkhead to protect thermalinsulation assemblies during installation and operation.
 34. Marineapparatus as claimed in claim 1 in which the equipment is an elongatepipeline comprising a plurality of short lengths of pipe joined end toend and a plurality of adjoined and affixed shrouded thermal insulationassemblies extending in length over the total of part length of theequipment.
 35. Marine apparatus as claimed in claim 1 in which the wallof the shroud is formed with one or a number of integral stiffeningwebs.
 36. Marine apparatus as claimed in claim 35 in which thestiffening webs are of circumferential and/or longitudinalconfiguration.
 37. Marine apparatus as claimed in any of the precedingclaims in which mass providing members or material are or isincorporated between the thermal insulation, ends of shroud, innersurface of shroud and the apparatus.